I 92 
opy 1 



THE HASTY 
* PERPETUAL*^ 



• FOR PRACTICAL USE EYERY BAY*. 



l^iifM^ 






THE HASTY 

PERPETUAL MENTAL CALENDAR, 

J FOR [ 

PRHCTICEL USE EVERY MY 

A SIMPLE, EASY METHOD WHICH WILE EX ABLE AXY OXE. 
TO DISPEXSE, WITH A 

PRINTED CALENDAR 

FOR ALL TIME TO COME. ALSO FI7RXISHIXG A 

MENTAL CALENDAR 

FOR EVERY YEAR OF THE CHRISTIAN ERA. VALUABLE IX DE- 

TECTING OR CORRECTIXG ERRORS IX DAYS. DATES 

OF MONTHS AXD YEARS. 






USEFUL TO \\A. Wlh) NEED A CALENDAR, ESPECIAL! 
BUSINESS MEN, TEACHERS, EDITORS, MINIS- 
TERS, LAWYERS, ETC. 



BY E. F. HASTY. 

ELKHART, - - - INDIANA. 

1885. 




P° 

[IF W 



C0 

p 



;• 



Entered according to Act of Congress, in the year 1885, 

in the Office of the Librarian at Washington, by 

E. F. HASTY, Elkhart, Indiana. 

ALL RIGHTS RESERVED. 



! PREFACE. i#=- 



1. This calendar method was invented about five 
years ago. Two years ago it was perfected, and as 
many have urged its publication it is now sent out. 

2. The method is simple, easily understood, and 
very little to memorize, especially as regards a large 
number of persons who are already familiar with some 
things required. A small degree of earnest attention 
will enable any one to use it who can understand the 
simplest tables and examples of arithmetic, and will 
dispense with the necessity of a printed calendar, in 
ordinary use, or a calendar clock. A printed Multi- 
plication Table will be about as necessary for daily use. 

3. So far as can be ascertained this is the first time 
that anything of the kind was ever published; for 
that reason explanations are rert/ full, especially for 
the benefit of young people who may desire to learn 
it : hence the numerous explanations may at first sight 
make it appear to be a very complicated method, 
which it is not as may be seen. 

4. Whoever is willing to learn the method of find- 
ing the t; Key Day'' (1st of January) of past and 
future years, has at command in his head a calendar 
for every year from 45 B. C. down for 2000 or 300O 
years to come, and that as really as if he had actually 
memorized a calendar for each year, so that he can 



IV PERPETUAL MENTAL CALENDAR. 

readily and easily tell the day of week of any date, or 
the date of any special day, when the year and month 
are given, or can tell anything else that can be learned 
from a printed calendar. 

5. It will be useful to those who instruct the blind, 
as has been already tested. 

6. It will enable any one, in very many cases, to 
detect, and often correct, errors in days and dates, 
and also to verify the correctness of others, especially 
where the day of the week is given. See examples in 
the back part of this manual. 

7. The author claims that this method is entirely 
original so far perhaps as anything of the kind can 
be original. He has had no similar method from any 
source to guide him, or even suggest, and hence no 
one else is in any sense responsible for its defects, or on 
the other hand can rightfully share in anything it 
contains of real merit. 






PERPETUHL MEHTEL CHLEEDRR, 



The calendar method, which is explained in the fol- 
lowing pages, is one in which special importance is 
attached to what is called, for convenience sake, the 
" Key Day" of a year. As the "Key Day" must be 
constantly used in every month and every week of the 
year, let every one know to a certainty what is meant 
by it and how to use it. 

The "Key Day ''' of any year, is always that day of 
the week which began, or will begin, that particular year. 

Sunday began the year 1882 ; therefore Sunday is the 
"Key" for that year. Monday began 1883, Tuesday 
1884, and Thursday 1885, and those days are the 
4 'Keys" of the respective years: 1886 will begin on 
Friday, 1887 on Saturday, and 1888 on Sunday, and 
those will be the "Keys" for those years, in the order 
named. 

The principle of this calendar method is. substantially, 
to have the first date, in each month, of the "Key." so 
perfectly in the memory that any other date or clay 
may be quickly found from it. 

In common years (a common year is any year that is 
not a Leap Year,) the same set of figures represents 
the first dates of u Keys v in the different months for 
all years in all centuries. 

For example, Sunday is the "Key" for 1882, there- 
fore the following figures will represent the first dates 
of Sunday in the months named for 1882, or any other 
common year of which Sunday is the "Key." The first 
date of Sunday in January, is 1st; February, 5th; 



D PERPETUAL MENTAL CALENDAR. 

March, 5th; April, 2d; May 7th, and June, 4th. The 
above dates, when put together, make 155,274. That 
set of figures represents the first dates of Monday in 
1883, Thursday in 1885, Friday in 1886, and Saturday 
in 1887, for the months named above. With the ex- 
ception of the first two (1 — 5) a different set of figures 
must be used for all Leap Years, as will be seen here- 
after. The "Key" for any current year is always 
known, or can be easily called to mind, but the method 
for finding the "Key" for any past or future year is 
explained on pages 14-22 

Before further explanations are given, the fol- 
lowing tables must be memorized and made very famil- 
iar, or this method cannot be used: 

TABLE OF MONTHS. 



7. July 31 Days 

8. August 31 Days 

9. September 30 Days 

10. October 31 Days 

11. November 30 Days 

12. December 31 



1. January 31 Days 

2. February* 28 Days 

3. March 31 Days 

4. April 30 Days 

5. May 31 Days 

6. June 30 Days 

*February has twenty-nine days in any Leap Year. 

The following, Table No. 1, gives the first date of 
the ' ; Key ;; for each month in any Common year, and 
must, therefore, be most used and should be memor- 
ized and made very familiar: 

TABLE NO. I. (FOR COMMON YEARS.) 

Jan, Feb. March. April. May. June. 

15 5 2 7 4 

July. Aug. Sept. Oct. Nov. Dec. 

2 6 3 1 5 3 

Table No. 2 gives the first date of the "Key" for 
each month in any Leap Year, and should also be 
memorized. 



PERPETUAL MENTAL CALENDAR. 
TABLE NO. II. (FOR LEAP YEARS.) 



Jan. 
l 


Feb. 
5 


March. 
4 


April. 
1 


May. 
6 


June. 
3 


July 

1 


Aug. 
5 


Sept. 

2 


Oct. 

7 


Nov. 
4 


Dec. 
2 



These tables are for perpetual use, applying to all 
years in any century. 

The figures in Table No. 1 make the following num- 
bers, which may aid in memorizing: 155,274 — 263,153. 
Table No. 2 makes the following: 154,163—152,742. 

There must be great care taken to associate the 
figures with their proper months, and in regular order 
as in the above tables. 



EXPLANATION NO. 1. 

Thursday is the " Key " for 1885, because it is the 
day of the week which begins the year ; 1885 is not a 
Leap Year, therefore we use " Table No. 1." The first 
date of Thursday in each month may be shown thus: 

January 1st Thursday. 

February 5th Thursday. 

March 5th Thursday. 

April 2d Thursday. 

May 7th Thursday. 

June 4th Thursday. 

Making, as we see, the numbers 155,274, and the dates 
for the other six months will make the other number 
263,153. 

Take the year 1882, which is not a Leap Year New 
Year's Day was Sunday, and Sunday is therefore the 
"Key" for 1882. 

The figures above represent the first dates of Sun- 
day in each month of 1882. The same is true of any 
other New Year's day or " Key Day v for any common 
year. 



8 PERPETUAL MENTAL CALENDAR. 

1884 was a Leap Year. Tuesday being the day 
which began the year is therefore the "Key" for 
1884. Hence we must use ''Table No. 2," which 
may be explained in the same manner as "Table No. 1." 

The first date of the ;t Key" for any month in the 
year having been memorized is therefore always 
known, hence any other date or day may be quickly 
found as previously stated. 

TAKE NOTICE !- -Any one who can easily and 
quickly tell the names of the days, and the dates, of 
the first seven days of each month, lias orprcome the 
most difficult part of this method. 

DATES GIVEN TO FIND THE DAY OF THE WEEK. 

1st Example. — Find the day for April 1, 1885. 
Thursday is Key for 1885. The first date of Thursday 
in April 1885 is the 2d. (See Table No. 1.) Therefore, 
if April 2 is Thursday, then April 1. is Wednesday. 

2d Example.— Find the day for May 6, 1885. The 
first date of Thursday in May. 1885. is the 7th. There- 
fore, May 6th must be Wednesday. 

3d Example. — Find the day for June 7, 1885. The 
first date of Thursday in June, 1885. is the 4th. There- 
fore. June 7th must be Sunday. 

4th Example.— Find the day for July 4, 1885. The 
first date of Thursday in July, 1885. is the 2d. There- 
fore the 4th must be Saturday. 

5th Example. — Find the the day for Nov. 2, 1885. 
The first date of Thursday in Nov., 1885, is the 5th. 
Therefore the 2d must be Monday. 



PERPETUAL MENTAL CALENDAR. y 

EXPLANATION NO. 2. 

TO FIND THE DAY OF WEEK FOR ANY DATE BEYOND 
THE VII. 

The numbers 7, 14, 21, and 28, may be designated as 
full week numbers or dates. Find the difference 
between the given date and the full week number or 
date next below; then find the day of the week for 
that difference. 

N. B. — If the given date is itself a full week date, 
14, 21 or 28, then find the day for the 7th, for whatever 
day has the 7th has also the 14th, 21st and 28th. 

1st Example. — Find the day for September 10 th, 
1885. The full week number below the 10th is the 7th. 
The difference between 7 and 10 is 3 ; therefore find the 
day for September 3d. The -fiist date of the " Key," 
Thursday, in September, 1885, is the 3d. Whatever 
day has the 3d has the 10th: therefore September 10th, 
1885, is Thursday. 

2d Example.— Find Hie day for October 18th, 1885. 
The difference between 14 and 18 is 4. Find the day 
for October 4th. The first date of Thursday in Octo- 
ber, 1885, is the 1st, therefore the 4th is Sunday, and 
October 18th, 1885. is Sunday. 

3d Example.— Find the day for November 23d, 1885. 
The difference between 21 and 23 is 2. Find the day 
for November 2d. The first date of Thursday in 
November, 1885, is the 5th. Therefore, the 2d is 
Monday. November 23d, 1885, is Monday also. 

4th Example.— Find the day for December 31st, 1885- 
The difference between 28 and 31 is 3. Find the day 
for December 3d. The first date of Thursday in 



10 



PERPETUAL MENTAL CALENDAR. 



December, 1885, is the 3d. Therefore, December 31st, 
1885, is Thursday, for whatever day has the 3d has 
also the 31st. 



EXPLANATION NO. 3. 

THE DAY OF THE WEEK GIVEN TO FIND THE DATE OF THE 
MONTH. 

To find the 2d, 3d, 4th and 5th dates of any given 
day in any month. Find the first date and add to 
that 7 for the 2d, 14 for the 3d, 21 for the 4th, and 
28 for the 5th. 

1st Example. — Find the date of the 1st Sunday in 
March, 1885. We know by "Table No. 1," that the 
first date of the " Key "—Thursday— for March, 1885, 
is the 5th. Therefore, the first Sunday in March, 
1885, is the 1st day of March. 

2d Example. — Find the date of the 3d Tuesday in 
April, 1885. The first Thursday in April, 1885, is the 
2d. Therefore, the first Tuesday is the 7th. Adding 
14 to 7 (see rule above) gives 21st for the 3d Tuesday 
in April, 1885. 

3d Example. — Find the date of the 4th Wednesday 
in September, 1885. The first Thursday in September, 
1885, is the 3d. Hence the first Wednesday must be 
the 2d. Adding 21 to 2 gives 23d for the fourth 
Wednesday in September. 1885. 

4th Example. — Find the date of the 5th Saturday in 
October, 1885. The first Thursday in October, 1885, is 
the 1st. Hence the first Saturday must be the 3d. 
Adding 28 to 3 gives the 31st for the fifth Saturday in 
October, 1885. 



PERPETUAL MENTAL CALENDAR. 11 

FURTHER EXPLANATIONS AND SUGGESTIONS TO AID IN THE 
RAPID AND EASY WORKING OF THIS CALENDAR. 

In order to be able to call to mind very quickly the 
present date in any month we must have reference to 
the "Key Date ,? of a month, and be able to know or 
call up instantly the " Key date " last passed over. 
After a little practice that will become a very easy 
thing and one can as readily have at command the 
month date, as the day of the week. 

The "Key Dates" for any month are found by 
adding 7. beginning with the first " Key Date " of 
a month. The first are given in Tables No. 1 and 2, 
which are presumed to be most thoroughly memorized. 

They are the same in January for both Leap Years 
and common years, as follows: 1, 8, 15, 22, 29. 

Each particular month in all common years has the 
same set of " Key dates. "' 

" Keys " change, but i; Key dates " do not. 

The same is true of Leap Years. Each month has 
its particular " Key dates " which never change. 

The " Key dates " for April in all common years are 
2. 9, 16, 23,^30. 

The "Key dates" for April in all Leap Years are 
1, 8, 15, 22, 29. 

It will, of course, be observed that some months 
have the same " Key dates " that others have. 

As the "Key date'' must be used in every week in 
the ordinary daily use of the Calendar, it will there- 
fore be found very helpful to fix in the mind, at the 
beginning of each year, the numbers which may be 
associated with the days of the week throughout that 
year, as will be explained below. Those numbers may 
be very quickly added to a "Key date" in order to 



12 PERPETUAL MENTAL CALENDAR. 

find the desired date of any particular da}', without the 
more slow process of passing from one day to another, 
sometimes over five or six days. 
Examples by way of explanation : 
1885. Thursday. •■Key.'" 1886. Friday. " Key." 

Friday 1 Saturday 1 

Saturday 2 S .,nday 2 

Sunday '. . . . 3 Monday '6 

Monday -1 Tuesday 4 

Tuesday 5 Wednesday 5 

Wednesday 6 j Thursday .6 

In the above if any one desires to know the date of 
Monday in any month or week of 1885 let him add 4 to 
the preceding "Key date/" for Tuesday add 5. for 
Wednesday add 6. etc. 

For 1886 the figures opposite the several days may 
be added, and for other years different numbers, until 
we come again to the same "Keys." 

Suppose that you have entered upon Wednesday in 
the last week of January, 1885, and you desire the date. 
Add 6 to your last "Key date." 22d. which gives the 
28th for Wednesday. 

Or if you desire to know the date of some Wednes- 
day a week or two in advance, always add 6. or what- 
ever number may be required for that year, to the 
preceding "Key date." prodded, of course, that pre- 
ceding "'Key date" is in the same month with 
Wednesday or other day whose date you desire to 
know. 

If you have in any case forgotten your last "Key 
date " in any month, you are always supposed to know 
your first "Key date," and any other one can be 
quickly found by adding 7. as already explained. 

It is well to be familiar with the regular week 



PERPETUAL MENTAL CALEXDAR. 13 

number of the days as well as their naines and 
order, as: Sunday. 1st day; Monday, 2d day; Tues- 
day, 3d day; Wednesday, 4th day; Thursday. 5th day; 
Friday, 6th day ; Saturday, 7th day. 

When the week number, and the month date, of any 
day are the same.it is very easy to find any day or 
date required. For example the 1st day of November. 
1885, is Sunday, therefore the week numbers and 
month dates, of the first week are the same, as follows: 

November 1st, Sunday, 1st day of week. 

November 2d, Monday, 2d day of week. 

November 3d, Tuesday, 3d day of week. 

The "Key," Thursday, being the 5th day of the 
month, also the 5th day of the week, any other day 
or date is readily found as is always the case when 
Sunday is the first day of the month. 

Become familiar with May and August in Common 
Years, and May and October in Leap Years, for they 
are the most difficult except when the week numbers 
and month dates are the same in any of them. 

To find the 1st when the ''Key date' 7 is the 7th r 
take the next day, for whatever day of week has the 
8th has also the 1st. Also if the "Key date"' is 5th or 
6th it may be convenient to run forward to the 8th. or 
to the 9th for the 2d, in preference to going backward. 

In months of 30 days, the days which are 1st and 
2d occur five times in that month. The 2d is always 
the last day of the month. The 3d is the 1st day of 
the following month. In months of 31 days, the days 
which are 1st, 2d, and 3d, occur five times in the month. 
The day having the 3d, always closes the month. The 
4th has the 1st of the next month. 

In February, of common years, whatever day is 7th 
is also last, and the day that begins February begins 



14 PERPETUAL MENTAL CALENDAR. 

also March and November. In Leap Years, the day 
that begins February also ends it. 

A little practice will enable you at a glance to see 
what date you must find the day of the week for, when 
3^our given date is beyond the 7th, as follows: When 
any given dates for which you desire to find the day 
of the week are 8. 15, 22, 29 you see in an instant that 
you may find the day for the 1st, or if they are 9, 16, 23, 
30, you find for the 2d. and so on. Therefore, dc not for- 
get that if you nan quickly find any day or date in 
the first week of any month you have substantially 
mastered all that is contained in the preceding pages. 



EXPLANATION NO. 4. 

HOW TO FIND THE " KEY " FOR AXY YEAR IN THE PAST 
OR FUTURE. 

Remember that the "Key" for any year is always 
the day which begins the year. 

The days of the week begin the years in an order 
that is perfectly systematic. The month dates of each 
month for different years pass from one day to another 
in the same systematic order. 

Let our own century — the 19th — be taken as a 
starting point in order to find the i; Key " for any year 
in other centuries. It may be regarded as a kind of 
"Century Key" for all other centuries. 

We find it most convenient to make special use of 
the Leap Years rather than common years. 

Unless there is strict care to distinguish between 
Leap Years and Common Years, there must be confu- 
sion and incorrect results. 



PERPETUAL MENTAL CALENDAL. 15 

HOW TO DISTINGUISH LEAP YEARS. 

Since the beginning of the Christian Era, any year, 
the last two figures of which may be divided by 4 r 
without a remainder, is a Leap Year : or any year that 
ends with 0, 4, or 8, preceded by an even number, as- 
1860, 1864, 1868, or that ends with 2, or 6, preceded by 
an odd number, as 1852, and 1856. 

Before Christ, 1, 5, 9, 13, 17, 21, etc., were Leap 
Years. The beginning of the iC Julian Calendar'* was 
about 45 B. C. 

THE ORIGIX OF OUR PRESENT CALENDAR, CALLED THE 
; 'GREGORIAN. " 

In 1582 Pope Gregory XIII determined to reform 
the Calendar, as there was a difference of many days 
between the Solar and Civil years. He made the cor- 
rection by suppressing ten days. He called October 
5th, (1582), October 15th. 

He then decreed that the Centesimal years should be 
counted as Leap Years, once in 400 years only; 1600 
was reckoned as a Leap Year, and 2000, 2400, etc., will 
be; but 1700 and 1800 were not; and 1900, 2100, 2200, 
etc., will not be Leap Years. 

All the Centesimal years from 1600, A. D., back to 
1 B. C, were Leap Years. 

It should be carefully noted that all Centesimal 
Years as 1700, 1800, etc., always end a century, instead 
of beginning one as many seem to think. 

The following table gives the unchanging order of 
the days of the week, as they become the "Key'' of 
the Leap Years in any century. The order must be 
memorized and made very familiar, which can be easily 
done by reciting backward the days of the week, each 
time omitting one dav. 



16 PERPETUAL MENTAL CALENDAR . 

TABLE NO. III. ORDER OF DAYS. 

1804, Sunday. 

1808, Friday. 

1812, Wednesday. 

1816, Monday. 

1820, Saturday. 
1824. Thursday. 
1828, Tuesday: 
1832, Sunday. 

Take any number of Leap Years in any part of any 
century* and the above represents the exact order in 
which the days of the week begin the years. 

The table also represents the order of the days for 
every fourth year without any regard to the Leap 
Years, as 

1809, Sunday. 

1813, Friday. 

1817, Wednesday. 

1821. Monday, etc. 

but the order will be mostly used with Leap Years, 
in passing up and down in a century. 

PASSING FROM ONE CENTURY TO ANOTHER. 

The above ' ' Table " also gives the order of days in 
passing from one century to another, since October 15, 
1582, New Style, as: 

1604, Thursday, 

1704, Tuesday,' 

1804, Sunday, 

1904, Friday. 

Each brace of four centuries after, is a duplicate of 

the above as 2004, Thursday; 2104, Tuesday, etc., etc. 

The first Leap Year of a century is always the 4th 

year, as 1704, 1804, etc. 

*The only exception to that is in the year 1582 the order of days 
is broken by the change in the Calendar which has already been 
named. 



PERPETUAL MENTAL CALENDAR. 17 

Having found the "Key" for the first Leap Year, 
you can easily run the " Keys " of the Leap Years in 
that century in the order given in " Table No. 3," and 
whoever can do so has accomplished the most difficult 
thing to be done in finding any desired "Key." 

SOLAR CYCLE. 

Twenty-eight years make a Solar Cycle: in that 
time the same days have the same dates throughout 
the year, and only in that time as regards the Leap 
Years. 

EXCEPTION TO THE ABOVE. 

In passing out of one century into another in the 
regular order of years, prior to 1582, in 28 years the 
same days had the same dates and there was no break 
made by the centesimal years, for they were all Leap 
Years. Since 1600 the centesimal years have not been 
Leap Years, and instead of there being an interval of 
28 years, in passing out of one century into another, 
the time is only 12 years with the two Leap Years 
closing a century, and 40 years with all the others. 

For Example. 1792, Sunday; 1796, Friday. 

In 12 years, which takes us into the next cen- 
tury, the same days again have the same dates, as 
1804, Sunday ; 1808, Friday. But we find 1784, Thurs- 
day, 1788, Tuesday, and only in 40 years again do 
those days and others throughout the year have the 
same dates as 1824, Thursday, 1828, Tuesday. 

The same is true of all the others, and the same 
principle applies to any other two centuries in New 
Style, where the Centesimal year over which you pass 
is not a Leap Year. 

Sunday being the "Key" of the first Leap Year, 
(1804), in this century, after each interval of 28 



18 PERPETCAL MENTAL CALENDAR. 

years, Sunday is again the "Key" of a Leap 
Year, as, 1804, 1832, 1860, 1888. 

The special use of those years, viz:, '4, '32, '60, '88, as 
reckoning points, will be of advantage in all centu- 
ries, for whatever is the "Key" of one is the "Key 1 ' of 
all, with the exception stated in foot note on page 16. 
1st Example.— Find the "Key" of 1812. 

1804. Sunday, (See Table Xo. 3. page 16) 
1808, Friday. 
1812, Wednesday. 
2d Example.— Find the "Key" for 1844. 
1832, Sunday. {Known Key.) 
1836, Friday. 
1840, Wednesday. 
1844, Monday. 
3d Example.— Find the "Key" for 1856. 
Knowing that 1860 has Sunday, we go back to 1856. 
Tuesday. 
4th Example.— Find the "Key" for 1880. 
1880. Thursday. 
1884, Tuesday.' 
1888, Sunday, (Known Key.) 
Beginning 1888, Sunday, and going back to 1880. 

RULE FOR FINDING THE "KEY*' FOR ANT LEAP YEAR. 

Begin with the "Key" of '4, '32, "60, or '88, which- 
ever of those years is nearest the desired year, and go 
forward or backward in the oi der of days given in 
"Table No. 3," page 16. 

ORDER OF DAYS FOR COMMON YEARS IN PASSING FROM 

ONE LEAP YEAR TO THE NEXT. 

TABLE NO. IV. 

1804, (Leap Year) Sunday I 1809 Sunday 

1805 Tuesday | 1810 Monday 

1806 Wednesday I 1811 Tuesday 

1807 Thursday 1812, (Leap Tear) . . . Wednesday 

1808. (Leap Year) Friday I 



PERPETUAL MENTAL CALENDAR. 19 

It is seen by the foregoing table that in going forward 
from a Leap Year one day must be passed over to find 
the "Key" of the first common year, then comes the 
regular order of the days of the week for four years, 
including the next Leap Year. 

In going backward from a Leap Year to common 
years, take the regular order of the days of the week 
backward for four years, including the Leap Year 
with which you begin. 

1st Example.— Find the "Key" for 1833. 

1832, Sunday. 

1833, Tuesday. 

2d Example.— Find the "Key'' for 1842. 
The nearest Leap Year is 1840. We find its "Key" 
and go forward to 1842, as follows : 

1832, Sunday, (Known Kev. I 
1836. Friday. 

1840, Wednesday. 

1841, Friday. 

1842, Saturday. 

RULE FOR FINDING THE "KEY " OF ANY COMMON YEAR. 

Find the "Key" of the nearest Leap Year, and go 
forward or backward to the desired year. 

BF°By carefully examining the order of days for 
Leap Years in " Table No. 3," the method of going, 
forward or backward over Leap Tear "Keys" may 
be shortened for some cases, but it is not given as 
a new rule. It applies only where you desire to go 
forward or backward several years from some known 
'"Key" to some year the "Key" of which is not 
known. Long steps may be taken in such cases as 
follows: In going forward from any known "Key" 

For 12 years after, take the next day. 

For 16 years after, take the day before. 

For 20 years after, take the third day before. 



20 PERPETUAL MENTAL CALENDAR. 

For example you want the "Keys" for 1872 
and 1876. 

1860, Sunday (Krown '"Key.'') 

1872, Monday (12 years after.) 

1876, Saturday (16 years after.) 

1880, Thursday (20 years after.) 

In going backward from any known i; Key, 11 exactly 
reverse the above. 

Thus 1860 Sunday (Known "Key.") 

1848 Saturday (12 years before) 

1844 Monday (16 years before) 

1840 Wednesday. ... (20 years before) 



EXPLANATION NO. 5. 

HOW TO FIND THE J ' KEY " FOPw ANY YEAR IN OTHER 
CENTURIES. 

It has been already shown on page 16 that the 
order of days is precisely the same in passing from one 
century to another since October 15, 1582, for each 
four centuries, for both Leap Years and Common 
Years, that is found with Leap Years in passing up 
and down in a century. 

For Example— 1604, Thursday. 
1704. Tuesday! 
1804. Sunday. 
1904, Friday. 

Again. 
2004, Thursday. 
2104. Tuesday. 
2204. Sunday. 
2304. Friday. 

Hence we find that each brace of four centuries — 
beginning with 1601 — has precisely the same days and 
dates. Therefore if we have a '"Key." or any other 



PERPETUAL MENTAL CALENDAR. 21 

day or date, it is the i; Key" day or date of the cor- 
responding year 400, 800, 1200, etc., years afterwards. 

Thus 1620, Wednesday is " Rev," 

2020, Wednesday is "Key," 
2420, Wednesday is '* Key.' 1 

RULE FOR FINDING A ' ' KEY " OR ANT OTHER DAY AFTER 
OCTOBER 15, 1582, — NEW STYLE. 

Find the k ' Key," or the day of the corresponding 
year in the nineteenth century and pass to the desired 
" Key " or day of another century in the order given 
in ''Explanation No. 5" above, or in "Table No. 3." 

If any one should prefer it, the " Key'' of the first 
Leap Year may be found, and then pass up or down 
in the century the same as given heretofore for the 
nineteenth century. 

1st Example.— Find the " Keys " for 1684, 1784, 1984- 

We know that the "Key" of 1884 is Tuesday. 
Hence we pass to the others required, thus: 

1684 Saturday. 

1784 Thursday. 

1884 Tuesday. 

1984 Sunday. 

2d Example.— Find the ;t Keys" for 1685, 1785, 1985. 

1685 Monday. 

1785 Saturday. 

1885 Thursday. 

1985 Tuesday. 

In 1st Example above the years are Leap Years, 
in the 2d Example they are Common Years, but the 
order of days is exactly the same as in u Table No. 3." 

The order of days in passing from one century to 
another prior to October 5, 1582 — Old Style — differs 
from the order afterward, but is more simple. It is 
the exact order of the day* of the /reek. 



22 PERPETUAL MENTAL CALENDAR. 

ORDER OF DATS IN PASSING FROM ONE CENTURY TO ANOTH- 
ER, "old style,' 1 beginning with 19th 

CENTURY, " NEW STYLE."' 

1804, Sunday, 
1504. Monday. 
1404, Tuesday, 
1304. Wednesday, 
1204, Thursday, 
1104, Friday, 
1004, Saturday. 
904, Sunday. 
It is seen by the above that it will be a very easy 
thing to find a " Key " or other day in a corresponding 
year in the 19th century and pass to any year of a 
century in "Old Style." 
Example.— Find the "Keys" of 1332, 1432, 1532. 
We know that the " Key " of 1832 is Sunday. Hence 
we find the others thus : 
1832, Sunday. 
1532, Monday, 
1432, Tuesday. 
1332, Wednesday. 

EXAMPLES FOR CORRECTION OF ERRORS, ETC. 

1st Example: — Haydn's "Dictionary of Dates," 
page 89, says that " Black Easter Monday" was April 
6, 1351. 

Find the day of week for April 6. 1851. The " Key" 
for 1852, (See Rule page 18) is Thursday, and the 
" Key" for 1851 is Wednesday. 

April 2, 1851, was Wednesday; (See "Table No. 1" 
page 6) hence April 6 was Sunday. 
April 6, 1851, Sunday, 
April 6, 1551, Monday, 
April 6, 1451, Tuesday, 
April 6, 1351, Wednesday, 
therefore " Black Monday " was April 4th. 



PPRPETUAL MENTAL CALENDAR. 2B 

2d Example. — Ridpath's and Bryant's Histories of 
the U. S. say that Juan Ponce De Leon discovered 
Florida on Easter Sunday, March 27, 1512. 

Find the day for March 27,1812. The " Key" of 
1812 is Wednesday. The first Wednesday in March, 
1812, is the 4th, and the 6th, is Friday. W T hatever is 
the 6th is the 27th. (See page 9.) 

March 27, 1812, Friday, 
March 27, 1512, Saturday. 

Therefore if the year is correct, it was March 28th. 
The probability is that it was discovered on March 27, 
1513, which was Sunday. (See Bancroft.) 

3d Example. — Bryant's History of the U. S. says, 
Vol. II, page 266, that " On Sunday, the first day of 
October, (1664), FortCasiniir surrendered." 

Find the day for October 1, 1864. Friday is " Key ,r 
for 1864. The first Friday in October, 1864, is the 
7th, (See Table No. 2 page 7) and the 1st is Saturday. 
October 1, 1864, Saturday, 
October 1, 1764, Monday, 
October 1, 1664, Wednesday. 
If it was "Old Style," then was October 1, 1664, Sat- 
urday, and October 1, 1665, was Sunday, for the days 
and dates of the 17th century, "Old Style," are identical 
throughtout with those of the 19th century, "New 
Style." (See Chart of " Keys.") 

4th Example: — Dr. Whedon's Commentary (Vol. 3, 
N. T., page 225,) says, "The passover feast closed on 
April 3 (58) which appears to have been Tuesday ; and 
Paul started from Philippi, on Wednesday April 4. 
The five days to Troas would terminate Saturday, 
April 8." Which day and date are correct? The 
"Key for 58 is Sunday, same as 1758, New Style. (See 
"Key Chart"). 



24 PERPETUAL MENTAL CALENDAR. 

April 2, 58, Sunday : April 3, Monday ; April 8, Sat- 
urday. Hence Saturday is correct, and Tuesday and 
Wednesday are not. 

Again it is said (page 230) that Paul landed at Tyre, 
"Monday, April 30'" (58). Whatever has the 2nd has 
the 30th. Therefore April 30, 58, was Sunday. 

5th Example. — An excellent lady from New Eng- 
land insists that her wedding anniversary comes only 
once in four years. She is equally confident that she 
was married on Sunday. Time Feb. 29. 1836. "Key" 
for 1836, Friday. Feb. 5th was Friday and Monday 
was also 1st and 29th. Feb. 29, 1836, Monday. 

6th Example. — Dec. 22d has been called "Fore- 
fathers" Day" because the "Pilgrim Fathers " landed on 
"Plymouth Rock," Dec. 11, 1620. O. S. Is Dec. 22d. 
"New Style.' 7 consistent with Dec. 11th. "Old Style," in 
1620? 

Find the day for Dec. 11. 1620. O. S. The ''Keys" 
and dates of the 17th century. O. S.. are the same a^ the 
19th century. N. S. 

"Key" for 1620, O. S., Saturday. First Date of Sat- 
urday in Dec, 1620, is the 2nd and the 4th is Monday, 
hence the 11th must be Monday. Dec. 11. 1620 O. S. 
Monday. 

Find the day for Dec. 22. 1620. N. S. "Key"" for 
1620 N. S. Wednesday. First date of Wednesday in 
Dec, 1620, N. S. is the 2d. and the 1st is Tuesday, the 
22d, must also be Tuesday. Dec. 22, 1620, N. S. 
Tuesday. 

The days of the week do not correspond. We find 
however that Dec. 21, 1620, N. S. is Monday. Hence 
we conclude that Daniel Webster should have deliv- 
ered his celebrated "Fore-fathers" Day" oration on Dec 
21. 1820, instead of on Dec. 22d. 



PERPETUAL MENTAL CALENDAR. 25 

7th Example. — M'Clintoek and Strong in their 
Cyclopaedia, Vol. 2, page 25, and Dr. De Puy in 
"People's Cyclopaedia,'' Vol. 1, under " Calendar/' 
tell us that Pope Gregory decreed that 1600 should 
not be reckoned as a Leap Year. They say, "begin- 
ning with 2000." Are they correct? 

If they are right and our "New Style" calen- 
dar from the present time back to 1600 has been cor- 
rect, then the "Key" of 1600 is Sunday, not Saturday 
as shown in the " Key Chart." 

Also the "Keys" for 1582 are Wednesday until 
October 5th, and Sunday after that date. 

In that case, Pope Gregory decreed that the change 
in the calendar should take place on Sunday. October 
5th. The " Key " also for 1504, 1532 and 1560 must be 
Wednesday and not Monday, as shown also in the "Key" 
Chart." That would change every " Key " for every 
year from 1582 back to 45 B. C. 

The "Key Chart" as it now stands is in perfect 
harmony in the main with every reliable historical 
writer, so far as compared, who gives the day of the 
week in connection with his dates. 

TEST EXAMPLES OX THE SUPPOSITION THAT 1600 WAS 
XOT A LEAP YEAR. 

1st. Whedon's Commentary (N. T. ) Vol. 3, pp. 225- 
230. gives the following days and dates: Saturday, 
April 8, 58: Monday, April 17,58: Thursday, April 
20. 58; Monday, April 24. 58: Wednesday, April 
26, 58. 

If the "Key'" for 1560 be Wednesday, according to the 
order of days previously explained, the "Key" for 
58 would be Tuesdav. 



26 PERPETUAL MENTAL CALENDAR. 

April 2d being Tuesday, April 8th would be Mon- 
day (not Saturday), April 17th would be Wednesday 
(not Monday). April 20th would be Saturday (not 
Thursday), etc. 

If. however, Sunday is the "Key" of 58, as must 
be if 1600 is reckoned as a Leap Year, the above will 
harmonize. 

2d. D'Aubigne says that Martin Luther was born 
on Monday, November 10th, 1483. If 1600 was a Com- 
mon Year, the -Key" of 1483 would be Friday. The 
first date of Friday would be the 5th. and Wednesday 
would be the 3d and 10th of November, and not 
Monday. If 1600 was a Leap Year, the " Key " of 1483 
would be Wednesday. Hence if Wednesday was the 
5th, Monday was the 3d and 10th. 

Let us suppose again that the days and dates as 
given by standard authors, prior to 1582, are in the 
main correct, and that 1600 was reckoned as a Common 
Year, then it must follow that days and dates as 
given by standard authors since 1582 "New Style," 
are in the main incorrect, and January 1st, 1885, 
should have been Wednesday instead of Thurs- 
day. 

The two periods certainly cannot be reconciled in 
their days and dates, as given by very many au- 
thors, except upon the basis that 1600 was a Leap 
Year. 

We therefore conclude that the Oyclopsedists, 
named above, are incorrect in saying that 2000 begins 
the Centesimal Leap Years since 1582, in accordance 
with the decree of Pope Gregory. 



PERPETUAL MENTAL CALENDAR. 27 

TABLE SHOWING THE REGULAR INTERVALS OF ANY DAY IN 
BEGINNING A YEAR. 

1804, Sunday, (Leap Year) 

1809, Sunday, 5 years 

1815, Sunday, 6 years }■ 28 Years. 

1826, Sunday, 11 years | 

1832, Sunday, (Leap Year) 6 years J 

1837, Sunday, 5 years ] 

1843, Sunday, 6 years j. 28 y 

1854, Sunday, 11 years f 

1860, Sunday, (Leap Year) 6 years j 



TABLE SHOWING THE REGULAR INTERVALS OF ANY DAY IN 

HAVING THE SAME DATE AFTER FEBRUARY, 

YEARS HAVING DIFFERENT "KEYS." 

1455, November 10, Monday "j 

1460, November 10, Monday, 5 years. 

1466, November 10, Monday, 6 years. } 28 Years. 

1477, November 10, Monday, 11 years. 

1483, November 10, Monday, 6 years. J 

1488, November 10, Monday, 5 years. ] 

1494, November 10, Monday, 6 years. I 9ft Ymt , o 

1505, November 10, Monday, 11 years. f zo lears * 

1511, November 10, Monday, 6 years. J 

Melancthon tells us tbat Martin Luther's mother was 
very confident of remembering the day and the hour 
when Martin was born. That it was Monday, Nov. 
10th, 11 p. m., but she was uncertain about the year. 
The family generally agreed that it was 1483. The 
"Key" for 1483 was Wednesday. The first date of 
Wednesday in November, 1483, was the 5th. Hence 
Monday was the 3d and 10th. 



^O PERPETUAL MENTAL CALENDAR . 

If lie was not born in 1483, and yet the day and date 
were certainly Monday, November 10, then the year in 
which he was actually born could not possibly have 
been nearer than 1477 or 1488. So much of a blunder 
they would not likely make. 

It may be seen by the above " Table " that if at any 
time you have the day of the week and the month 
dale given, and you have lost the year, and know 
that it must be one of five years, you can readily find 
the year; or again, you may find it within a range of 
6 or 11 years. 

The foregoing examples have been given to suggest 
the manner in which this Calendar may detect and 
often afford valuable aid in correcting errors in days 
and dates, and also in verifying the correctness of 
others. Whoever may learn it will be surprised at the 
numberless instances in which it may be used in ordi- 
nary business affairs, and especially in the reading of 
newspapers, magazines and books, embracing days and 
dates. 



CENTURIES HAVING THE SAME KEYS AND OTHER DAYS 
AND DATES. 

It may be of advantage to observe and remember 
that the "Keys" and other days and dates of the fol- 
lowing centuries, as grouped, are exactly the same. 
Hence, when you have a "Key" or other day or date in 
any one of the group, you have it in all those grouped 
with it. 



PERPETUAL MENTAL CALENDAR. 29 

TABLE OF GROUPED CENTURIES HAVING THE SAME "KEYS*' 
OR DAYS AND DATES. 

1601, New Style. I 1701. New Style. 

501, Old Stvle. 1. Old Style. 

1201, Old Style. I 701, Old Style. 

I 1101. Old Style. 

1801. New Style. I 1901. New Style. 

201. Old Stvle. I 401, Old Stvle. 

901 i Old Style. I 1101. Old Style. 

1601, Old Style. \ Oct. 15. 1582. to 1600 N.S. 

301, Old Stvle. j 101, Old Style. 

1001, Old Style. | 801. Old Style. 

1701. Old Style, I 1501. Old Style. 

To Sept, 3d." 1752. Old Style. | 

45, B. C. Old Stvle. 
601. Old Stvle. 
1301, Old Style. 

In the above, if you have a "Key" or other day or 
date in the century beginning with 1801. you have it 
also for the corresponding year or time in the centu- 
ries beginning with 201. 901, 1601, O. S. If you there- 
fore desire a day or date in the century beginning with 
1, as in 4th example, page 23, where the "Key" for 58 
is desired, find the "Key" for 185S and then quickly 
pass to 1758, according to the order of days previously 
explained, and you have the "Key" for 58. 

Or you may find it in 1858 and that gives the "Key" 
for 258 and from that year can easily pass to 58. 

In the practical use of this Calendar, different per- 
sons will have suggested to them various ways of 
abbreviating and thereby expediting the mental 
work. 



30 PERPETUAL MENTAL CALENDAR. 

AMERICAN REVOLUTIONARY BATTLES, ETC., ON SUNDAY. 

It has been sometimes stated that battles that were 
fought, or that were begun, on Sunday, usually went 
against the party that brought on the engagement. 
Those who wish to do so, may study the following and 
ascertain whether it has been true in our own country. 

Quebec, Dec. 31, 1775, "Key" Sunday 

Boston (British fled), March 17, 1776, "Key" ..Monday 

Fort Mifflin, Nov. 16, 1777, "Key" Wednesday 

Monmouth, June 28, 1778. "Key" Thursday 

Kettle Creek (Ga,), Feb. 14, 1779. "Key" Friday 

Stono Ferry, June 20, 1779. "Key" Friday 

Chemung (Indians;, Aug. 29. 1779. "Key" Friday 

Rocky Mount, July 30, 1780. "Key" . . * Saturday 

Hanging Rock, Aug. 6, 1780, "Key" Saturday 

LAST WAR WITH ENGLAND. 

Detroit (Surrendered) Aug. 16, 1812 

Pimartains Town Oct. 18, 1812 

Elizabethtown Feb. 7, 1813 

Burlington Heights June, 6, 1813 

Hampton June 13, 1813 

Black Rock July 11, 1813 

Fort Niagara Dec. 19, 1813 

Horse Shoe Bend March 27, 1814 

Fort Erie ■-■-... July 3, 1814 

Plattsburg Sept. 11, 1814 

Rodriguez's Canal (New Orleans) Jan. 1, 1815 

New Orleans Jan. 8-13, 1815 

AMERICAN CIVIL WAR. 

Bull Run July 21, 1861 

Mill Spring Jan. 19, 1862 

Fort Donelson Feb. 16, 1862 



PERPETUAL MENTAL CALENDAR. 31 

Hampton Roads March 9, 1862 

Pittsburg Landing April 6-7, 1862 

Winchester (Ya.) May 25, 1862 

Cross Keys and Port Republic June 8-9, 1862 

South Mountain Sept. 14, 1862 

Prairie Grove (Ark.) Dec. 7, 1862 

Chickasaw Bayou Dec. 27-29, 1863 

Arkansas Post Jan. 11, 1863 

Big Black (Miss.) May 17, 1863 

Port Fisher (N. C.) Dec. 25, 1864 

Port Pisher Captured Jan. 15, 1865 

Hatcher's Run Feb. 5, 1865 

Petersburg (Va.) April 2, 1865 



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Table of Leap Year "Key Days" from 45 B. C. to A. DJ.752 "Old Style," and from A. D. 1582, to A. D; 2000 "New Style." 



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!, England corrected its Calendar by suppressing 11 days. September 3, 
dar by suppressing 



was called 

10 days. October 5, 



14. Wednesday was "Key" for 
was called Oct. 15. Monday was " 



1752 up to September 3. 
Key" for 1582 up to Oct. 



Saturday \ 
. Friday > 



LIBRARY OF CONGRESS 



022 008 895 9 • 



